Various types of such a seat drive device have been proposed conventionally. As an example, Patent Document 1 describes a seat drive device with three positioning mechanisms (including two vertical positioning mechanisms arranged on the front side and the rear side and one fore-and-aft positioning mechanism). Output shafts to these positioning mechanisms can be drivably coupled to a single rotary motor through corresponding electromagnetic clutches and gear mechanisms.
Specifically, as shown in FIG. 42, operation switches 201, 202 and 203 related to operations on corresponding positioning mechanisms energize a single rotary motor 204 with polarities corresponding to directions of operations on the operation switches 201, 202 and 203. Further, the operation switches 201, 202 and 203 energize solenoids 206, 207 and 208 respectively of electromagnetic clutches to drivably couple output shafts to these positioning mechanisms and the rotary motor 204. This causes the rotary motor 204 to drive the positioning mechanisms through the electromagnetic clutches and gear mechanisms, so that an appropriate positioning mechanism performs positioning.
Patent Document 2 describes a seat drive device with two positioning mechanisms (two vertical positioning mechanisms arranged on the front side and the rear side). As shown in FIG. 43, output shafts 211 and 212 to the corresponding positioning mechanisms can be drivably coupled to a single rotary motor through a differential gear mechanism 215. The motion of the differential gear mechanism 215 is switched by two locking mechanisms 213 and 214 provided for the output shafts 211 and 212 respectively. Specifically, the differential gear mechanism 215 has an input channel coupled to the rotary motor and two output channels coupled to the corresponding ones of the output shafts 211 and 212 of the positioning mechanisms.
For actuation of one of the positioning mechanisms, in order to lock the output shaft 211 (212) to the other positioning mechanism, a plunger 213a (214a) of the pertinent locking mechanism 213 (214) is actuated. Then, the output shaft 211 (212) to the other positioning mechanism is coupled to the rotary motor through the differential gear mechanism 215 in a manner that disables drive by the rotary motor, so that the appropriate positioning mechanism performs positioning.
Patent Document 3 describes a seat drive device with two positioning mechanisms (including a reclining mechanism and a fore-and-aft positioning mechanism). As shown in FIG. 44, an output shaft 221 to one of the positioning mechanisms contacts two friction wheels 222 and 223 and permits movement of the friction wheels 222 and 223 while contacting the friction wheels 222 and 223. A spring 224 extends under tension between the friction wheels 222 and 223. A control knob 225 to move the friction wheels 222 and 223 is provided between the friction wheels 222 and 223. The control knob 225 is linked through an actuating plate 227 and an operation lever 228 to an operation button 226 relating to the aforementioned positioning mechanism. In response to operation on the operation button 226, the actuating plate 227 moves back and forth depending on the direction of the operation while the operation lever 228 swings. This makes the control knob 225 move the friction wheels 222 and 223 to couple one of the friction wheels 222 and 223 to a rotary shaft R of a rotary motor M in a manner that enables drive by the rotary motor M.
Likewise, an output shaft 231 to the other positioning mechanism contacts two friction wheels 232 and 233 and permits movement of the friction wheels 232 and 233 while contacting the friction wheels 232 and 233. A spring 234 extends under tension between the friction wheels 232 and 233. A control knob 235 to move the friction wheels 232 and 233 is provided between the friction wheels 232 and 233. The control knob 235 is linked through an actuating plate 237 and an operation lever 238 to an operation button 236 relating to the other positioning mechanism. In response to operation on the operation button 236, the actuating plate 237 moves back and forth depending on the direction of the operation while the operation lever 238 swings. This makes the control knob 235 move the friction wheels 232 and 233 to couple one of the friction wheels 232 and 233 to the rotary shaft R of the rotary motor M in a manner that enables drive by the rotary motor M.
The operation buttons 226 and 236 are linked through the actuating plates 227 and 237 respectively to a switch SW that energies the rotary motor M and discontinues energization of the rotary motor M. In response to operations on the operation buttons 226 and 236, the actuating plates 227 and 237 move back and forth depending on directions of the operations, thereby energizing the rotary motor M simultaneously with appropriate polarities.
As an example, for actuation of one of the positioning mechanisms, the pertinent operation button 226 (236) is operated and this moves the friction wheels 222 and 223 (232 and 233) together with the control knob 225 (235). Then, one of the friction wheels 222 and 223 (232 and 233) corresponding to the direction of the operation is linked to the rotary shaft R and the rotary motor M is energized with a polarity corresponding to the direction of the operation, so that the rotary shaft R is coupled to the output shaft 221 (231) through the appropriate friction wheel 222 or 223 (232 or 233). As a result, the aforementioned positioning mechanism performs positioning. This also applies to actuation of the other positioning mechanism.